for snow water equivalent - Sommer Mess-Systemtechnik

More documents

Recommendations

Info

Snow Pack Analyser (SPA) for snow water equivalent (SWE) and liquid water content Sommer GmbH & Co KG Straßenhäuser 27 A-6842 Koblach Wolfram SOMMER 1 , Reinhard FIEL 1 1 Sommer Mess-Systemtechnik, Strassenhaeuser 27, A-6842 Koblach, Austria 1. ABSTRACT Improved estimation of the spatial snow water equivalent (SWE) distribution is a key task in current snow research. Quantifying the complex variability of the SWE both in time and space is essential for hydropower production, risk assessment with regard to natural hazards (avalanches, floods, debris flows), as well as for tourism issues in alpine areas. The Snow Pack Analyser (SPA) is an automatic in-situ measurement system to determine the characteristics of snow covers. Along a flat ribbon sensor the complex capacitances at low and high frequencies are measured for real-time determination of the snow density, snow water equivalent and liquid water content. The system can operate with up to four sensors. They are either installed sloping through the complete snow cover or they are arranged horizontal at the ground or defined levels. The combination of sensors allows to optimize the information on specific tasks. The determination of the liquid water content in the snow cover is unique. In periods of thaw the liquid water content rises. This enables a forecast of the point in time when the water runoff of the snow starts and provides important information for rationing of reservoirs, flood prediction or for avalanche services to estimate wet slab avalanches. 2. INTRODUCTION Efficient energy management of hydro power resources requires accurate forecasting of water capacity from snow melt and run-off. At present the precision of melt water prognoses for hydro power reservoirs is between 30 and 50 %. As an example, a 10 % gain in forecast precision at the ‘La Grande Rivière’ catchment in Quebec (Canada) would correspond to a yield of 2,2 TWh. Improved accuracy of SWE measurements will enhance the economic efficiency of hydro power plants or drinking water reservoirs as well. Prognosis of melt water run-off are relevant for flood prevention. Not only mountainous and alpine regions are affected by floods, but all the areas where rivers are fed by these catchments. As an example, rapid snow melting in the Alps is known to be one reason for flooding along the River Rhine valley from Germany to the Netherlands. The precise monitoring and modeling of SWE, liquid water content and the point in time of water run-off will enhance the accuracy of flood predictions and may reduce the danger or effects of natural catastrophes. The determination of liquid water content in the snow cover or in the ground layer of the snow cover is an additional parameter to SWE. It is an indicator for avalanche services to predict wet snow avalanches in periods of thaw, especially in spring. Moreover, the realization of long-term monitoring helps to reduce dangerous and expensive adoption of human resources in the wintry area. 2 / 10 +43 (0)5523 55989-0 office@sommer.at www.sommer.at
3. HISTORICAL OVERVIEW The initial development of the SPA was performed during the international EU-funded research project SNOWPOWER [1][2][3] in the years 2001 to 2004. The objective of the project was to increase the precision of filling prognosis to at least 20% by calibrating remote sense data with ground truth data determined by a new snow measurement method. A new electromagnetic sensor allowing a monitoring of an area of up to 2000 m² was developed. A PC Software to calculate the snow water equivalent SWE and density from field data was written. Based on the results and experiences with the laboratory-scale instrument, a new field measurement instrument was designed. Field tests were carried out during three winter periods at two measurement sites in Switzerland and Canada. The measurement site at the Weissfluhjoch in Davos was operated by the Swiss Federal Institute for Snow and Avalanche Research (SLF). It was a high Alpine test field and harsh winter conditions with air temperatures below -20 °C and wind speeds of 25 to 30 m/s occurred occasionally. Intermediate snow melt was rare during the accumulation phase. The main melts started in April wetting the snow pack from its top to the bottom. The second measurement site was located in the Bras d’Henri watershed in Quebec [4]. The conditions were arctic, the field had a smooth surface with a maximum slope of 0.5 %, and the snow cover remained relatively dry. Continuous measurements of snow depth and snow temperatures were conducted at both sites throughout the entire investigation period. Also air temperature, wind speed, relative humidity, solar radiation and precipitation were recorded automatically. At Weissfluhjoch, a detailed snow profile description was made twice a month. At these occasions, snow density, SWE, snow temperature and the degree of wetness were determined manually for each snow layer. Outflow of melt water from the snow pack was measured continuously in a lysimeter of 2x2-m ground area. At the test field in Canada, six snow cores were collected twice a week to measure snow depth, the mean snow density and the SWE. At the same time, a detailed snow profile description was made to determine the liquid water content, density and temperature at every 10 cm, using a denoth meter, snow density sampling and the dial stem thermometer. These field test with its accurate data collection resulted in a prototype for the measurement system. In the years 2004 to 2008 the system was continuously improved by Sommer Mess- Systemtechnik. The sensor and its installation were re-engineered, the calculation algorithm was improved, and the measurement and controlling device was designed to calculate the parameters in situ. In 2009 the SPA system was finalized. Sommer GmbH & Co KG Straßenhäuser 27 A-6842 Koblach 3 / 10 +43 (0)5523 55989-0 office@sommer.at www.sommer.at
Page 1: Snow Pack Analyser (SPA) for snow w
Page 5 and 6: 4.1.3. Configuration Examples Commo
Page 7 and 8: 4.2.2. Snow density The density mea
Page 9 and 10: 4.2.4. Forecast of water run-off At

for snow water equivalent - Sommer Mess-Systemtechnik

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?